1. Field of the Invention
The present invention relates generally to wind turbine technology, and more particularly to a blade for use in a wind turbine having increased efficiency and utility.
2. Description of the Prior Art
Particularly within the past decade or so, it is becoming increasingly clear that alternatives to fossil fuels to generate electricity are needed and that this need is becoming more critical with each passing year. The pollution caused by the burning of fossil fuels to generate electricity has already created significant destruction to the environment resulting in global warming, which if not stopped or reduced significantly, could well lead to disastrous declines in the quality of life of billions of people around the world. The supply of fossil fuels is constantly being depleted, and as the demand for electricity continues to surge dramatically in countries such as China, the cost of fossil fuels will continue to rise and the supply of fossil fuels will become more scarce.
In addition to nuclear and solar energy, the use of wind energy to generate electricity has long been considered and has already found widespread use. The supply of wind is unlimited, free in cost, widely available and free of pollutants. The conventional wind turbine electrical generator includes a group, typically three, of aerodynamically shaped blades mounted for rotation atop a tower. The blades are mounted at one of their ends to a hub, which, in turn, drives the rotor of an electrical generator. As the prevailing wind passes over the blades they are caused to rotate, which, in turn, causes the rotor to turn in the generator, thereby to generate electricity in a known manner. The electricity thus generated is collected for transmission to a local facility for further transmission along power lines to the consumers of the electricity.
Although it has clear advantages over fossil fuel, such as its unlimited supply and freedom from pollutants, the use of wind power has thus far been limited as a result of the relatively high cost of generation of electricity and the relatively low yield for the monies invested in building wind turbines. One problem in the use of wind turbine technology to generate electricity occurs when the velocity of the ambient wind is too low to drive the turbine blades to generate a sufficient amount of energy. A second problem arises when the wind velocity is too great, which could result in the damage or even destruction of the wind turbine. When the latter condition occurs, the wind turbine is typically shut down until the wind velocity returns to normal levels. It is thus not unusual for a wind turbine to achieve only about 30% of its energy-generation capacity. Moreover, even at normal wind velocities, the efficiency of conventional wind turbines to produce significant amounts of electricity at competitively low costs is limited by the current technologies.
As a result of the inherent advantages of wind turbine technology numerous attempts have been made over the past decades to improve the various elements of the wind turbine, particularly to improve the blade design, including the use of blades having hollow interiors. Although the efficiency of generation of electricity by wind turbines has steadily increased, it has not yet reached levels at which wind turbine technology can compete widely with fossil fuels.
There thus remains a need for an improved wind turbine that can operate more efficiently at all levels of wind velocity, thereby to greatly increase the use of wind turbine technology as an economically viable alternative to fossil fuels in the generation of electricity.
It is thus an object of the present invention to provide a blade for a wind turbine that allows the turbine to operate at a higher efficiency and at a reduced unit cost.
It is another object of the invention to provide a wind turbine blade that allows the wind turbine to be used more effectively over a wide range of wind velocities, thereby increasing the yield and utility of the turbine over greater periods of usage.
It is also an object of the invention to provide a wind turbine blade that allows the turbine to be used to generate electricity in the event of dangerously high wind conditions as well as at low wind velocities.
It is a further object of the invention to provide a wind turbine design in which the blade interior space is converted into a pressurized air chamber giving exit of air from the blade interior through valves located along one edge of the blade so that streams of air are expelled from the blade at high speed.